There have conventionally been known semiconductor light emitting apparatuses in which a semiconductor light emitting element is covered with a fluorescence-containing material which is resin including a fluorescent material, and the fluorescent material is excited (an electron orbit changes from a low energy state to a high energy state) by ultraviolet light and/or visible light emitted from the semiconductor light emitting element so that the fluorescent material emits light. The fluorescence-containing material is formed and shaped by spin coating or screen printing. By the spin coating, however, the maximum layer thickness of the fluorescence-containing material is limited to around 100-900 μm, and the fluorescence-containing material can be formed and shaped only on the upper surface of the substrate. On the other hand, by the screen printing, the fluorescence-containing material can be formed and shaped not only on the upper surface of the substrate but also around the periphery of the substrate, and the fluorescence-containing material can be evenly formed and shaped with the layer thickness of 0.3 to 0.5 mm.
The screen printing is concretely disclosed in the patent document 1 (Japanese Laid-Open Patent Application No. 2002-185048; published on Jun. 28, 2002) and the patent document 2 (Japanese Laid-Open Patent Application No. 2004-82514; published on Mar. 18, 2004). That is to say, the patent documents 1 and 2 disclose a method such that a screen plate is provided on an application target, and an applied material on the screen plate is pushed out through holes made through the screen plate and applied to the application target. Japanese Laid-Open Patent Application No. 2000-233489 (published on Aug. 29, 2000) discloses a method such that a rubber pallet termed squeegee is moved back and forth so that an applied material provided on a screen plate is pushed though holes of the screen plate and applied to an application target.
As discussed above, comparing the spin coating and the screen printing, the screen printing is advantageous for forming and shaping a fluorescence-containing material. For this reason, the screen printing is widely used for forming and shaping a fluorescence-containing material around a semiconductor light emitting element.
Formation and shaping of a fluorescence-containing material around a semiconductor light emitting element is disclosed in the patent document 4 (Japanese Laid-Open Patent Application No. 2003-179269; published on Jun. 27, 2003), the patent document 5 (Japanese Laid-Open Patent Application No. 2002-134792; published on May 10, 2002), and the patent document 6 (Japanese Laid-Open Patent Application No. 2005-123238; published on May 12, 2005). More specifically, the patent document 4 discloses a method to form and shape a fluorescence-containing material by using a mask as the screen plate. The patent document 5 disclose a method to form and shape a fluorescence-containing material by using a metal mask as the screen plate. The patent document 6 discloses a method such that a semiconductor light emitting element is provided at the center of each of plural openings made through a screen plate termed stencil, the stencil is removed after the openings are filled with a fluorescence-containing material, and the fluorescence-containing material is hardened so that the fluorescence-containing material is formed and shaped around the semiconductor light emitting element.
The following will closely discuss the method of manufacturing a semiconductor light emitting apparatus recited in the patent document 6, with reference to FIG. 8. FIG. 8 is a cross section of the semiconductor light emitting apparatus, for describing the manufacturing method of the patent document 6. As shown in FIG. 8, the manufacturing method of the patent document 6 is arranged such that, in order to cover a light emitting surface of a semiconductor light emitting element 100 with a fluorescent layer 102, a fluorescent layer forming template (stencil) 101 having openings 103 which are used for forming the fluorescent layer 102 is provided on a substrate 104 on which the semiconductor light emitting element 100 is mounted. Then the openings 103 of the fluorescent layer forming template 101 are filled with a fluorescence-containing material, the filled fluorescence-containing material is hardened, and the fluorescent layer forming template 101 is removed from the substrate 104. As a result, the fluorescent layer 102 is formed.
However, in an apparatus which forms and shapes a fluorescence-containing material around a semiconductor light emitting element by the screen printing disclosed by the patent document 1, 2, 3, 4, or 5, the viscosity of the fluorescence-containing material significantly varies in accordance with the ambient temperature, and a sedimentation condition of sediment in the fluorescence-containing material also varies (i.e. a fluorescent material with a high gravity settles down). The sediment is kept settled down if the fluorescence-containing material is not stirred. As a result, the density of the fluorescence-containing material becomes uneven, and hence the fluorescence-containing material applied around the semiconductor light emitting element does not have an even mixture ratio. On this account, color and light emission of a semiconductor light emitting apparatus which emits light by the semiconductor light emitting element are uneven.
In the meanwhile, the semiconductor light emitting apparatus recited in the patent document 6 uses, for injection, a fluorescence-containing material whose viscosity is varied and hence the mixture ratio is disproportionate. On this account, bubbles may enter or be generated in a space between the fluorescence-containing material and the semiconductor light emitting element. As a result, the fluorescence-containing material injected to the opening of the stencil may be deformed and bubbles may be generated in the fluorescence-containing material.